BR112020014501A2 - OPTICAL FIBER, AND OPTICAL FIBER COATING PROCESS - Google Patents

Abstract

optical fiber comprising: an optical waveguide comprising a glass core surrounded by a glass cover; a coating around said optical fiber guide which comprises a polymeric material comprising a cured polyester obtained by: (a) esterification of reagent (a) selected from carboxylic acids, triglycerides and mixtures thereof, which contains a chain aliphatic c16-c24 comprising at least two conjugated double bonds, with a reagent (b) selected from polyols containing at least three hydroxyl groups, wherein the polyols are thermally stable up to 300 ° c; and (b) curing the polyester obtained in this way, in the presence of a transition metal salt, in which the transition metal is selected from mn, fe, co, cu and ni. preferably, the curing step is thermal curing, preferably up to 300 ° C. the transition metallic salt acts as a curing accelerator, that is, it increases the curing speed, in order to coincide with the deposition speed of the optical fiber, the temperature of the glass that leaves the deposition stage and the height of the deposition commonly used in industrial installations for the production of optical fibers.

Description

OPTICAL FIBER, AND FIBER COATING PROCESS OPTICS FIELD OF THE INVENTION

[001] The present invention relates to an optical fiber that has a cross-linked polyester coating. The polyester coating can be cured by radiation or, more conveniently, thermally cured. The optical fiber according to the present invention is a valuable alternative to optical fibers coated with conventional polymeric materials that need to be cured by means of controlled temperature radiation, such as UV-curable acrylate polymer materials.

BACKGROUND OF THE INVENTION

[002] Optical fibers commonly comprise a glass core, within which the transmitted optical signal is confined, surrounded by a cover (typically with a diameter of about 120-130 µm), preferably made of glass. The combination of core and cover is usually identified as an “optical waveguide”. The optical waveguide is generally protected by a coating, typically of polymeric material, which protects the glass fiber against the external environment and provides resistance to physical handling forces, such as those encountered when the fiber is subjected to cabling operations. The coating "typically comprises a first coating layer positioned in direct contact with the coating, also known as a" primary coating ", and at least a second coating layer, also known as a" secondary coating ", that surrounds the first coating. In the art, the combination of primary coating and secondary coating is sometimes also identified as a “primary coating system”, as these two layers are generally applied during the process of making the fiber by deposition. In this case, oThe coating in contact with the coating is called "internal primary coating", while the coating in contact with and around the internal primary coating is called "external primary coating". In some cases, a single coating can be applied in contact with the coating. Then, the term “primary coating” should designate the primary primary coating and the term “secondary coating” should designate the primary external coating.

[003] Generally, the primary coating is made of relatively soft material that has a modulus of elasticity E 'relatively low at room temperature (typically 0.1 MPa to 5 MPa) and low Tg, for example, less than -20 " *Ç. The secondary coating is generally formed by a more rigid polymer which has a higher E 'modulus of elasticity at room temperature (typically 500 MPa to 2000 MPa) and a higher glass transition temperature (Tg) compared to the coating layer primary.

[004] For certain applications, the optical waveguide can be coated with a single coating layer that has modulus of elasticity and Tg values that are intermediate between the primary coating and the secondary coating. The general diameter of the optical waveguide with the primary and secondary coating can be from 150 pum to 250 pm.

[005] The polymeric materials generally used to form primary coatings, secondary coatings and single layer coatings are obtained from compositions comprising oligomers and acrylate monomers that are cross-linked by means of UV radiation in the presence of an appropriate photoinitiator. Acrylate polymer coatings should, however, be formed on the optical waveguide at relatively low temperatures, such as at room temperature at around 50 “C, and cured in the presence of an inert atmosphere (for example, under nitrogen gas ) in order to avoid thermal degradation of polymeric materials and to ensure proper adhesion of the coating layer to the optical waveguide. These restrictions require the use of special devices to control the temperature during the polymer deposition and curing process. Typically, radiation curing furnaces receive a continuous flow of inert gases (for example, nitrogen or helium) in order to maintain the necessary conditions.

[006] The need for the stringent operating conditions described above apparently makes the process of making optical fibers and the apparatus used to conduct this process somewhat expensive and complex.

BRIEF DESCRIPTION OF THE INVENTION

[007] The Depositor faced the problem of providing an appropriate polymeric material for the formation of coating layers on optical fibers that can be cured under relatively high temperature, either thermally or by radiation, in order to simplify the process of manufacturing guides. coated optical waves.

[008] In particular, the Depositor faced the problem of supplying appropriate polymeric material for the formation of coating layers on optical waveguides that is heat-curable, so that it can be applied to the optical waveguide without using radiation devices, such as such as UV ovens, which require precise temperature control and the presence of inert gas.

[009] The Depositor concluded that the above problems and others that will arise more clearly from this specification can be solved by polymeric materials containing certain polyesters such as oligomeric units that can be cured by means of heat or radiation, in the presence of salt transition metal. The transition metallic salt, which may contain an organic or inorganic anion as a counterion, acts as a curing accelerator, that is, it increases the curing speed, in order to coincide with the speed of deposition of the optical fiber, the temperature of the glass that leaves the deposition stage and the height of the deposition tower commonly used in industrial installations for the production of optical fibers.

[010] When cured by heat, the polymeric material according to the present invention has the advantage of being applicable during the process of depositing the fiber before the cooling of the deposited fiber close to room temperature and for exploiting the heat of the newly glass fiber -deposited as a heat source for curing.

[011] When cured by means of radiation, The polymeric material according to the present invention has the advantage of allowing the use of less controlled operating conditions, particularly during the curing step, as these polymers have less sensitivity to thermal degradation, even when cured in the presence of oxygen.

[012] polymeric materials cured according to the present invention have mechanical properties, particularly elasticity and adhesion to the glass surface of the fiber, which make the coated optical fiber suitable for use over a wide temperature range (for example, from - 60 ºC to +150 ºC). The polymeric coating materials according to the present invention can be used as a primary, secondary or single coating, preferably as primary and single coatings of optical fibers.

[013] According to the present invention, the polyester according to the present invention can be obtained by means of an esterification reaction between a selected long chain unsaturated residue and a selected polyol. By changing the relative ratios of these reagents, polymeric materials that have the desired mechanical properties can be obtained. The properties of the final polymer can also be adjusted by selecting appropriate curing temperatures and curing times, which influence the crosslink density of the polymer.

[014] Second first aspect, therefore, the present invention relates to an optical fiber comprising: - an optical waveguide comprising a glass core surrounded by a glass cover; and - a coating around said optical waveguide which comprises a polymeric material which comprises a cured polyester obtained by means of: a. esterification of reagent (A) selected from carboxylic acids, triglycerides and mixtures thereof, containing a Ci-Ca aliphatic chain comprising at least two conjugated double bonds, with a reagent (B) selected from polyols containing at least three hydroxyl groups, in which the polyols are thermally stable up to 300 ºC; and b. curing of the polyester obtained in this way, in the presence of a transition metallic salt, in which the transition metal is selected from Mn, Fe, Co, Cu and Ni.

[015] In one embodiment, the curing of the polyester is carried out thermally, for example, under a temperature of up to 300 ҼC.

[016] In an alternative embodiment, curing of the polyester can be conducted by means of radiation, such as UV radiation.

[017] According to a second aspect, the present invention relates to an optical fiber coating process which comprises: - providing an optical waveguide comprising a glass core surrounded by a glass cover; - application of curable coating composition on the coating, in which the said coating composition comprises a polyester obtained by esterifying reagent (A) selected from carboxylic acids, triglycerides and mixtures thereof, which contain a Ci6s- aliphatic chain Coa comprising at least two conjugated double bonds, with a reagent (B) selected from polyols containing at least three hydroxyl groups, where the polyols are thermally stable until

300 ºC; and - curing the aforementioned curable coating composition in the presence of transition metal salt, in which the transition metal is selected from Mn, Fe, Co, Cu and Ni, in order to cross-link said polyester and form the coating.

[018] In one embodiment, curing of the curable coating composition is carried out thermally, for example, under a temperature of up to 300 "C.

[019] In an alternative embodiment, curing of the curable coating composition can be conducted by means of radiation, such as UV radiation.

[020] Unlike known acrylate-based fiber optic coatings and typically obtained by the reaction of polyisocyanate, (poly) alcohol, (meta) acrylate monomer and photoinitiator, often in the presence of viscosity adjusting agents and / or diluents and / or adhesion promoters, to provide an urethane (meta) acrylate oligomer that is mixed with at least one reactive diluent to provide the fiber optic coating material, the fiber optic coating material accordingly with the present invention it is based on only two classes of main components, reagents A and reagents BE. Obtaining an optical fiber coating based on acrylate with appropriate mechanical properties, for example, as a primary coating, requires the consideration of a large number of variables. The mechanical properties of the coating material according to the present invention can be adjusted by simply changing the ratios in a given pair of reagent A and reagent B.

[021] This process makes it possible to obtain a coating "of optical fiber that has mechanical properties suitable for use as a primary coating, secondary coating or single coating, by selecting a certain amount of reagent A, such as alpha-ellosteric acid , and a certain amount of reagent B, such as trimethylolpropane ethoxylate 450, and conducting an esterification reaction.The resulting polyester is cured and its mechanical properties are measured, such as elastic modulus E ', glass transition temperature or both If these properties do not match the desired coating or a coating with different “mechanical properties” is then required, the ratio (ratio) of reagent A: reagent B can be changed to obtain a coating material with the desired mechanical properties.

[022] For the purposes of the present invention and the appended claims, the words "one" or "one" are used to describe elements and components of the present invention. This is done merely for convenience and to provide a general sense of the present invention. This specification and the claims should be read as including one or at least one and the singular also includes the plural, unless it is obvious to indicate otherwise.

[023] For the purposes of this specification and the following claims, unless otherwise indicated, all figures expressing values, quantities, percentages, etc. they must be understood as modified, in all cases, by the expression “about”. In addition, all ranges include any combination of the maximum and minimum points described and include any of their intermediate ranges, which may or may not be specifically indicated herein.

[024] For the purposes of the present invention and the following claims, “thermally stable up to 300 ° C” indicates that a substance heated to 300 ° C, in air and under atmospheric pressure, has a weight loss of 0% by weight at 2% in weight of your weight. Weight loss can be calculated, for example, by means of thermogravimetric analysis (TGA; 20 ºC / min).

[025] For the purposes of this specification and the appended claims, the values of elastic modulus E '"and Tg are intended to be determined by means of Dynamic Mechanical Thermal Analysis (DMTA) in tension. Tg is derived from the curve of DMTA obtained using the target value method.

DETAILED DESCRIPTION OF THE INVENTION

[026] According to the present invention, the appropriate reagent (A) is carboxylic acid, triglyceride or one of its mixtures, which contains a C1-6 Ca1 aliphatic chain comprising at least two conjugated double bonds. The Depositor noted that a reagent (A) that does not contain chains with at least two conjugated double bonds is unsuitable for the purposes of the present invention, as the polyester derived from its esterification with polyol as reagent (B) is not sufficiently crosslinkable or is only crosslinkable after curing times too long for convenient industrial application.

[027] Preferably, the carboxylic acid containing a C1i6-Ca aliphatic chain comprising at least two conjugated double bonds as reagent (A) is monocarboxylic acid.

[028] Carboxylic acid that contains a Cis-Co aliphatic chain that comprises at least two conjugated double bonds as reagent (A), for example, is alpha-eleostearic acid (a-ESA; 9Z11E13E-18: 3), calenic acid (8E10E12Z7-18: 3), punicic acid (9E11E13Z-18: 3) or licanic acid (4-keto-octadeca-9,11,13-trienoic acid). Alpha-eleoesteearic acid is preferred.

[029] In one embodiment of the present invention, Reagent (A) is triglyceride or a mixture of triglycerides comprising at least one C1-6 aliphatic chain comprising at least two conjugated double bonds. Vegetable oils or seed oils can contain these triglycerides or a mixture of triglycerides in an amount of 30% by weight to 80% by weight.

[030] Conveniently, reagent (A) is a mixture of triglycerides containing at least 70% by weight, based on the total weight of said mixture, of at least one Cis-Ca aliphatic chain comprising at least two conjugated double bonds . When the amount of Ci Ca aliphatic chains comprising at least two conjugated double bonds in an oil is less than 70% by weight, known methods can be applied to concentrate the polyunsaturated conjugated part, for example, by means of fractional crystallization .

[031] Triglyceride mixtures containing the above amount of C1i6s-Ca1 aliphatic chains comprising at least two conjugated double bonds are commercially available, for example, in the form of tung oil, pomegranate seed oil, calendula oil and their mixtures.

[032] The use of triglyceride or its mixture as a reagent (A) may be convenient in relation to the use of carboxylic acid, as triglycerides are usually more easily available and less expensive than the corresponding carboxylic acids.

[033] Reagent B, which is a polyol containing at least 3 hydroxyl groups, in which the polyol is thermally stable up to 300 ° C, is preferably a polyol containing 3 to 9, more preferably 3 to 6 hydroxyl groups .

[034] The hydroxyl groups of the polyol may be primary, secondary or tertiary hydroxyl groups, preferably primary or secondary hydroxyl groups and, more preferably, primary hydroxyl groups. Primary hydroxyl groups exhibit higher reactivity among the three types of hydroxyl groups. Thermally stable polyols are known in the art.

[035] Examples of reagent (B) according to the present invention are glycerol ethoxylate, glycerol propoxylate, trimethylolpropane ethoxylate, dipentaerythritol and mixtures thereof.

[036] Preferably, glycerol ethoxylate and glycerol propoxylate have an average numerical molecular weight (Mn) of 800 to 1200 (determined by GPC analysis).

[037] Preferably, trimethylolpropane ethoxylate has an average numerical molecular weight (Mn) of 100 to 1200.

[038] Conveniently, the reagent (B) according to the present invention is in liquid form at room temperature. The liquid form of the reagent (B) promotes physical mixing with the reagent (A) and helps to obtain a homogeneous-looking polyester.

[039] The polyol as reagent (B) according to the present invention is thermally stable at 300 ºC. The polyol as reagent (B) according to the present invention can be thermally stable, even at temperatures above the limit provided, but its stability within the limit mentioned above must be present.

[040] To prepare the polyesters according to the present invention, the reagents (A) and (B) react under esterification conditions.

[041] Preferably, when the reagent (A) is carboxylic acid with a C6-Cx aliphatic chain comprising at least two conjugated double bonds, the ratio between the reagent (A) and reagent (B) is one mole of reagent (A ) per hydroxyl group contained in reagent B.

[042] The number of hydroxyl groups contained in the reagent (B) can be determined using known methods of measuring the content of free hydroxyl groups in a chemical, which are normally based on the number of milligrams of potassium hydroxide required to neutralize the acetic acid removed by acetylation of a gram of a chemical substance that contains free hydroxyl groups.

[043] When reagent (A) is triglyceride or a mixture of triglycerides containing a Cis-Co aliphatic chain comprising at least two conjugated double bonds, the esterification between reagents (A) and (B) for the preparation of polyesters of according to the present invention is a transesterification reaction. The reaction conditions are substantially the same as those used for the esterification reaction between reagents (A) and (B), when the first is carboxylic acid.

[044] Preferably, when reagent (A) is triglyceride or a mixture of triglycerides containing at least one Cie-Ca aliphatic chain comprising at least two conjugated double bonds, reagent (A) reacts with reagent (B) in molar ratio A / B within the range of 1: 1 to 1: 3, where A is expressed in number of moles of triglycerides that contain at least one chain comprising at least two conjugated double bonds and B is expressed as the number of polyol moles.

[045] The esterification reaction can be conducted using methods and devices well known to those skilled in the art. Preferably, the esterification reaction between the reagent (A) and the conductor (B) is conducted in the presence of catalyst, such as acid or base, preferably a base, suitable for esterification of carboxylic acids or triglycerides with polyols. Examples of catalysts are: metal hydroxides, alkoxides and carbonates, alkaline tert-butoxide, rare earth oxides, rare earth salts and transition metal salts, organometallic, amines, guanidines and the like.

[046] Conveniently, the catalyst of the present esterification reaction is in liquid form at room temperature.

[047] Preferably, the catalyst of the present esterification reaction is a titanium or tin catalyst. Examples of preferred catalysts according to the present invention are: organo tin oxides, hydroxides and alkoxides (such as dibutyltin oxide, dibutyltin laurate and dibutyltin dilaurate), titanium tetraisopropoxide and mixtures thereof.

[048] Preferably, the catalyst is used in quantities within the range of 0.1 to 3 mol%, based on the total moles of the carboxylic acid present in the reaction mixture, when the carboxylic acid is used as such, or 0, 1 to 0.8 mol% of triglycerides present in the reaction mixture.

[049] The esterification reaction is carried out under temperature preferably in the range of 50 to 250 “C.

[050] Preferably, the esterification reaction is conducted under pressure within the range of 1 atm to 4 atm.

[051] Preferably, the esterification reaction time is within the range of 2 hours to 48 hours.

[052] Preferably, the esterification reaction is conducted in the absence of any added solvent, in order to avoid any contamination of the polymer coating applied on the optical waveguide.

[053] Preferably, the polyester according to the present invention is thermally cured. Thermal curing can be conducted through the application of thermal radiation (for example, infrared radiation) or heat transfer (for example, heat transfer from a heated fluid, such as hot air). Thermal curing is preferably carried out at a temperature of up to 300 ºC, more preferably within the range of 80 ºC to 300 * C and, even more preferably, within the range of 120 ºC to 300 "ºC.

[054] Alternatively, the polyester according to the present invention can be cured by radiation, for example, by applying ultraviolet radiation, X-rays, electron beams and the like. According to another possible embodiment, the polyester according to the present invention can be cured by means of thermal curing combined with radiation curing.

[055] According to the present invention, the curing step of the polyester obtained by means of step (a) is carried out in the presence of a transition metal salt, in order to cross-link said polyester and form the coating. The transition metal is selected from: Mn, Fe, Co, Cu and Ni.

[056] Regarding the counterion of the transition metal, it can be inorganic, such as bromide, iodide, sulfate, phosphate and carbonate chloride.

[057] Preferably, the counterion of the transition metal is an organic anion, such as: C2-C1g carboxylates and acetylacetonate.

[058] The use of organic anion is convenient, as it promotes the dissolution or dispersion of the transition metallic salt in the polyester obtained through step (a) of esterification.

[059] Preferably, the transition metal is present in an amount ranging from 100 ppm to 2000 ppm, more preferably from 200 ppm to 1000 ppm.

[060] To prevent premature curing of the polyester, the transition metallic salt is added to the polyester after the end of step (a) and completely mixed to obtain stable and complete dissolution or dispersion of the accelerator in the polymer.

[061] The mixture is preferably carried out at a temperature of 20 * C to 120 ºC, more preferably from 50 ºC to 90 ºC. To increase the dissolution or dispersion of the transition metal salt in the polyester obtained by step (a), the transition metal salt is preferably pre-dispersed in the organic phase, more preferably in a long chain carboxylic acid, triglyceride or its compounds. mixtures. Preferably, the long chain carboxylic acid or triglyceride is selected from those used as reagents (A) according to the present invention.

[062] The transition metallic salt acts as a curing accelerator, that is, it increases the curing speed, in order to coincide with the deposition speed of the optical fiber, the temperature of the glass leaving the deposition stage and the height of the deposition tower commonly used in industrial installations for the production of optical fibers. This makes the process for producing optical fibers according to the present invention particularly convenient in terms of productivity, while still allowing operation at a lower temperature during curing with respect to a corresponding process in which the transition metal salt is absent.

[063] Curing of polyester can also take place by means of a screen in the presence of oxygen. Oxygen can behave as a reticle initiator or adjuster. The desired final properties of the cured polymer can also be adjusted by varying the curing temperature and curing time, as these two parameters influence the curing density of the curing reaction and, therefore, the degree of curing of the polymer.

[064] Optionally, curing of the polyester can be carried out in the presence of a thermal free radical initiator. A cationic initiator can be used simultaneously.

[065] Thermal initiators are preferably used which have an activation temperature within the range of 60 ºC to 300 ºC. Examples of thermal initiators that can be used for the purposes of the present invention are: 2.2 '"- azobis (2-methylpropionitrile) meso-1,2-dibromo-1,2-diphenylethane and tetra-alkyl-1,2- diphenylethanes.

[066] Examples of cationic initiators that can be used for the purposes of the present invention are iodonium derivatives.

[067] When using a thermal initiator, a thermosetting composition comprising a polyester and a thermal initiator is prepared, wherein said initiator is preferably present in an amount of 0.3% by weight to 8% by weight, more preferably from 0.5% by weight to 5% by weight, based on the weight of the thermosetting composition.

[068] As the second preferred embodiment, the cured polymer material of the coating is obtained by UV curing of the polyester according to the present invention, particularly in the presence of photoinitiator. Conventional photoinitiators can be used in the present invention. Examples of suitable photoinitiators include benzophenone and / or acetophenone derivatives, such as alpha hydroxy alkylphenyl ketones, benzoyl and benzyl alkyl ethers, monoacylphosphine oxides and bisacylphosphine oxides. Preferred photoinitiators are 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one and diphenyl oxide (2,4,6-trimethylbenzoyl phosphine).

[069] When using a photoinitiator, a UV-curable composition comprising a polyester and a photoinitiator is prepared, wherein said photoinitiator is present in an amount of 0.3% by weight to 8% by weight, most preferably from 0.5% by weight to 5% by weight, based on the weight of the curable composition.

[070] The curable coating compositions according to the present invention can also include other conventional additives in effective amounts. For example, additives such as stabilizers, leveling agents, adhesion promoters, chain transfer agents, dyes including pigments and dyes, viscosity adjusting agents, wetting agents and the like can be used.

[071] The curable composition according to the present invention can be prepared by mixing the components with any appropriate method known in the art.

[072] After curing, the polymers obtained have mechanical properties, elasticity and adhesion properties that make them suitable as coating layers for optical fibers. Particularly, the polymeric materials cured according to the present invention have an elasticity modulus (E '") and glass transition temperature that meet the needs of use as primary coating layers, secondary coating layers or single coating layers. , the coating materials according to the present invention are used as primary coating layers and single coating layers.

[073] When used as a primary coating layer, the cured polymer material according to the present invention preferably has an elastic modulus (E '") at 25 ºC of 0.01 to 5 MPa, more preferably 0.05 at 5 MPa, and glass transition temperature (Tg) of -20 ºC maximum, and preferably, maximum 30 “ºC.

[074] When used as a single coating layer, the cured polymer material according to the present invention preferably has an elastic modulus (E) at 25 ºC of 20 to 200 MPa, more preferably 30 to 150 MPa, and temperature glass transition (Tg) of maximum 20 ºC and, preferably, maximum 0 "ºC.

[075] When used as a secondary coating layer, the cured polymer material according to the present invention preferably has an elastic modulus (E '") at 25 ºC from 500 to 2000 MPa and a glass transition temperature (Tg) of more than 50 “C.

[076] When the polyester according to the present invention is used to form a primary coating on an optical fiber, a secondary coating can also be applied around said primary coating, using the polymeric materials conventionally used in the art for manufacturing secondary coatings , such as a secondary UV-curable acrylate coating.

[077] Secondary coating useful in the fiber according to the present invention, in combination with a thermally curable primary coating, may comprise a polymer selected from methacrylate polymer, acrylate polymer and mixtures thereof. In particular, the secondary coating comprises urethane acrylate polymers which can be obtained, for example, by means of radiation curing of a radiation-curable composition comprising an oligomer having a main chain derived from polypropylene glycol and a polyester polyol based in dimeric acid. A material suitable for the secondary coating of the optical fiber according to the present invention is described in WO 2012/036546 or marketed as DeSoliteO 3471-2-136.

[078] The manufacture of the coated optical fiber according to the present invention can be carried out according to known methods. After deposition of the optical waveguide, for example, a primary coating can be applied by passing the optical waveguide through a sizing mold and a reservoir containing the curable composition according to the present invention. When using a thermally curable composition, the application can be conveniently carried out when the optical waveguide has an appropriate temperature, such as from 150 ºC to 300 “ºC, in order to exploit the heat of the deposited optical waveguide to obtain the final cured polymeric material. When applying a radiation curable composition or polymer, the application step is followed by radiation curing (for example, by UV or IR) of the applied composition in order to obtain the final polymer material. In the case of deposition of primary and secondary coating, the latter is applied to the primary coating before or after curing of the secondary coating (using methods known as wet to dry or wet to wet deposition).

[079] The optical fiber produced in this way can be used in the production of optical cables. The fiber can be used as is or in the form of tapes comprising several fibers combined together by means of a common coating.

[080] This specification discloses only a few embodiments of an optical fiber coated in accordance with the present invention. Appropriate modifications of these embodiments can be made according to specific technical needs and application needs without departing from the scope of the present invention.

[081] The present invention will become totally clear after reading the following example, with reference to the attached Figure 1, which shows the curing behavior of some coatings according to the present invention.

EXAMPLES

[082] Polyesters according to the present invention were prepared using the following procedure.

[083] A reaction mixture was prepared by mixing at room temperature (25 ºC) a triglyceride, polyol and an esterification catalyst.

[084] The triglyceride was tung oil. That is, a mixture of 82% by weight of α-eleoesteearic acid, 8% by weight of linoleic acid, 5% by weight of palmitic acid and 5% by weight of oleic acid ( the weight percentages refer to the weight of the oil).

[085] The polyol was TMPE 170 (trimethylolpropane ethoxylate: number average molecular weight (Mn) = 170) which has the formula: 9 Trimethylolpropane ethoxylate 170 = TMPE 170

[086] The esterification catalyst was dibutyltin laurate (DBTL).

[087] The quantities of the above reagents and catalyst were as follows: - tung oil: 70% by weight; - TMPE 170: 29% by weight; and - DBTL: 1% by weight; wherein the weight percentage is expressed with respect to the total weight of the composition. The esterification reaction was carried out at a temperature of 150 ºC for 12 hours.

[088] After the esterification reaction, samples of the resulting polyester with different accelerators were added in the quantities reported in Table 1. The mixture of the accelerator with the polyester was conducted at 70 ºC long enough to achieve complete dispersion of the transition metallic salt. TABLE 1 Sample Quantity Accelerator accelerator (mol%) (*) tetrahydrate acetylacetonate E ses FEI ns (*) molar percentage of transition metal in relation to the total moles of fatty acids present in the triglyceride.

[089] The cure rate of the resulting compositions was evaluated by means of a parallel plate rheometer (TA Instruments AR 2000ex) under heating at a temperature of 200 ҼC (cure temperature). The cutting storage module (G ') was measured as a function of time. The curves are reported in Figure 1, where G '(expressed in Pa, in the ordinate) is reported as a function of time (sec, in the abscissa). The numbering of the curves in Fig. L1 refers to the samples in Table 1.

[090] As a reference, a sample of the polyester obtained after esterification without any accelerator was also analyzed (the curing curve is also reported in Figure 1 as “A”).

[091] In Table 2 below, the values for the time to start the cure (corresponding to the point at which the cure starts, with an appreciable increase in the G 'value) are also reported. It is evident that the addition of the accelerator markedly reduced the time for the curing to start and, therefore, accelerated the curing process.

TABLE 2 me HAVE Sample (sec) 2 <30

ELLE IL AND EE

[092] For each cured polyester sample, films were obtained using an automatic coating device with a micrometer blade configured to obtain a film thickness of 50 to 200 microns. The modulus of elasticity (E ') at -30 ºC, +25 ºC and +100 ºC and the glass transition temperature (Tg - starting point) of each cured film as determined by DMTA analysis are reported in Table 3.

[093] Comparative results obtained in commercial primary coating films Cl (DP1l014-XS from DSM) and single coating SC (3471-3-14 from DSM) are also reported in Table 3. These reference materials were cured using UV radiation using the curing conditions indicated by the supplier.

TABLE 3 Sample Tg (ºC) res qe 6

. Sample Tg (“C) rs qe | A | to | eme ao o Ts

Claims (16)

1. FIBER OPTICS, characterized by comprising: - an optical waveguide comprising a glass core surrounded by a glass cover; and - a coating around said optical waveguide which comprises a polymeric material which comprises a cured polyester obtained by means of: a. esterification of reagent (A) selected from carboxylic acids, triglycerides and mixtures thereof, containing a Cis-Cax aliphatic chain comprising at least two conjugated double bonds, with a reagent (B) selected from polyols containing at least three hydroxyl groups, in which the polyols are thermally stable up to 300 “C; and b. curing of the polyester obtained in this way, in the presence of a transition metallic salt, in which the transition metal is selected from Mn, Fe, Co, Cu and Ni. 2. FIBER OPTICS, according to claim 1, characterized in that the mentioned curing step is thermal curing, preferably up to 300 “ºC. 3. FIBER OPTICS, according to claim 2, characterized by the thermal curing being conducted under temperature in the range of 80 ºC to 300 “C. FIBER OPTICS according to claim 1, characterized in that the reagent (A) is monocarboxylic acid. 5. FIBER OPTICS, according to claim 1, characterized in that the reagent (A) is an acid selected from alpha-eleoesteearic acid, calendic acid, punicic acid or licanic acid. 6. FIBER OPTICS, according to claim 1, characterized by the reagent (A) being a mixture of triglycerides that contain at least 70% by weight, based on the total weight of the mentioned mixture, of C 6 -n Cas aliphatic chains comprising “at least two conjugated double bonds. 7. FIBER OPTICS, according to claim 1, characterized in that the reagent (B) is a polyol containing 3 to 9 hydroxyl groups. 8. FIBER OPTICS, according to claim 1, characterized in that the hydroxyl groups of the polyols are primary hydroxyl groups. 9. FIBER OPTICS, according to claim 1, characterized in that said reagent (B) is selected from: glycerol ethoxylate, glycerol propoxylate, trimethylolpropane ethoxylate, dipentaerythritol and their mixtures. 10. FIBER OPTICS, according to claim 1, characterized in that the transition metal salt is present in an amount ranging from 100 ppm to 2000 ppm. 11. FIBER OPTICS, according to claim 1, characterized in that said coating is selected from primary coating and single coating. 12. FIBER OPTICS according to claim 1, characterized in that said coating is a primary coating which is surrounded by a secondary coating, wherein said secondary coating comprises a polymer selected from methacrylate polymer, acrylate polymer and mixtures thereof . 13. OPTICAL FIBER COATING PROCESS, characterized by comprising: - providing an optical waveguide comprising a glass core surrounded by a glass cover; - application of a curable coating composition on the coating, in which the said coating composition comprises a polyester obtained by esterifying reagent (A) selected from carboxylic acids, triglycerides and mixtures thereof, which contain a Cis- Ca comprising at least two conjugated double bonds, with a reagent (B) selected from polyols containing at least three hydroxyl groups, in which the polyols are thermally stable up to 300 ºC; and - curing the aforementioned curable coating composition in the presence of transition metal salt, in which the transition metal is selected from Mn, Fe, Co, Cu and Ni, in order to cross-link said polyester and form the coating. 14. PROCESS according to claim 13, characterized in that the reagent (A) is carboxylic acid that has a C1is-C21 aliphatic chain comprising at least two conjugated double bonds and the ratio between the reagent (A) and the reagent (B) is one mole of reagent A per hydroxyl group included in reagent B. 15. PROCESS according to claim 13, characterized in that the reagent (A) is triglyceride or a mixture of triglycerides containing at least one Cis-Co aliphatic chain comprising at least two conjugated double bonds and reagent A reacts with reagent (B) in molar ratio A / B in the range of 1: 1 to 1: 3, where A is expressed as the number of moles of triglycerides that contain at least one chain comprising at least two conjugated double bonds and B is expressed as the number of moles of polyol. 16. PROCESS, according to claim 13, characterized by the curing of the curable composition being thermal curing under a temperature of up to 300 “ºC.